Image reading apparatus utilizing three color channel circuitry to capture four color channels of image data

1. An image reading apparatus for effecting line reading in a main scanning direction by scanning in a sub-scanning direction to thereby read the image of an original, the apparatus including: a photoelectric conversion device for resolving an optical signal representative of an inputted line image into a number of basic colors exceeding a predetermined number and outputting them as analog electrical signals; an analog/digital conversion circuit for inputting said predetermined number of the analog electrical signals differing from one another at a time, and converting respective ones of the analog electrical signals into digital signals; and a selection circuit for selecting the analog electrical signals equal to or less than said predetermined number from the output of said photoelectric conversion device at each image reading of one main scanning line and also selecting the analog electrical signals of a different combination at the reading of the images of both adjacent main scanning lines, and outputting them to said analog/digital conversion circuit, wherein said photoelectric conversion circuit is configured to resolve the inputted optical signal into four basic colors and outputting them as analog electrical signals, and said analog/digital conversion circuit is configured to input up to three analog electrical signals at a time, and converting them into digital signals, and wherein said selection circuit selects first and second analog electrical signals from the output of said photoelectric conversion device at the reading of the image of a first main scanning line, and selects third and fourth analog electrical signals from the output of said photoelectric conversion device at the image reading of a second main scanning line adjacent to said first scanning line.

2. An image reading apparatus for effecting line reading in a main scanning direction by scanning in a sub-scanning direction to thereby read the image of an original, the apparatus including: a photoelectric conversion device for resolving an optical signal representative of an inputted line image into a number of basic colors exceeding a predetermined number and outputting them as analog electrical signals; an analog/digital conversion circuit for inputting said predetermined number of the analog electrical signals differing from one another at a time, and converting respective ones of the analog electrical signals into digital signals; and a selection circuit for selecting the analog electrical signals equal to or less than said predetermined number from the output of said photoelectric conversion device at each image reading of one main scanning line and also selecting the analog electrical signals of a different combination at the reading of the images of both adjacent main scanning lines, and outputting them to said analog/digital conversion circuit, wherein said photoelectric conversion circuit is configured to resolve the inputted optical signal into four basic colors and outputting them as analog electrical signals, and said analog/digital conversion circuit is configured to input up to three analog electrical signals at a time, and converting them into digital signals, wherein the light inputted to said photoelectric conversion device is transmitted light from an original film to which light has been applied, said photoelectric conversion device includes four single-color photoelectric conversion devices corresponding to said four basic colors, respectively, and said four single-color photoelectric conversion device accumulate therein charges corresponding to the inputted light for predetermined accumulation times differing from one another, and wherein said selection circuit selects the analog electrical signals outputted from two devices of said four single-color photoelectric conversion devices which are shortest and second shortest in said predetermined accumulation time, at the image reading of a first main scanning line, and selects the analog electrical signals outputted from the devices other than said selected two devices of said four single-color photoelectric conversion devices, at the image reading of a second main scanning line adjacent to said first main scanning line adjacent to said first main scanning line.

3. An image reading apparatus for effecting line reading in a main scanning direction by scanning in a sub-scanning direction to thereby read the image of an original, the apparatus including: a photoelectric conversion device for resolving an optical signal representative of an inputted line image into a number of basic colors exceeding a predetermined number and outputting them as analog electrical signals; an analog/digital conversion circuit for inputting said predetermined number of the analog electrical signals differing from one another at a time, and converting respective ones of the analog electrical signals into digital signals; and a selection circuit for selecting the analog electrical signals equal to or less than said predetermined number from the output of said photoelectric conversion device at each image reading of one main scanning line and also selecting the analog electrical signals of a different combination at the reading of the images of both adjacent main scanning lines, and outputting them to said analog/digital conversion circuit, wherein said photoelectric conversion circuit is configured to resolve the inputted optical signal into four basic colors and outputting them as analog electrical signals, and said analog/digital conversion circuit is configured to input up to three analog electrical signals at a time, and converting them into digital signals, wherein the light inputted to said photoelectric conversion device is transmitted light from an original film to which light has been applied, said photoelectric conversion device includes four single-color photoelectric conversion devices corresponding to said four basic colors, respectively, and said four single-color photoelectric conversion device accumulate therein charges corresponding to the inputted light for predetermined accumulation times differing from one another, and wherein said selection circuit selects the analog electrical signal outputted from one device of said four single-color photoelectric conversion devices which is shortest in said predetermined accumulation time, at the image reading of a first main scanning line, and selects the analog electrical signals outputted from the devices other than said selected one device of said four single-color photoelectric conversion devices, at the image reading of a second main scanning line adjacent to said first main scanning line.

4. An image reading apparatus for effecting line reading in a main scanning direction by scanning in a sub-scanning direction to thereby read the image of an original, the apparatus including: a photoelectric conversion device for resolving an optical signal representative of an inputted line image into a number of basic colors exceeding a predetermined number and outputting them as analog electrical signals; an analog/digital conversion circuit for inputting said predetermined number of the analog electrical signals differing from one another at a time, and converting respective ones of the analog electrical signals into digital signals; and a selection circuit for selecting the analog electrical signals equal to or less than said predetermined number from the output of said photoelectric conversion device at each image reading of one main scanning line and also selecting the analog electrical signals of a different combination at the reading of the images of both adjacent main scanning lines, and outputting them to said analog/digital conversion circuit, wherein said photoelectric conversion circuit is configured to resolve the inputted optical signal into four basic colors and outputting them as analog electrical signals, and said analog/digital conversion circuit is configured to input up to three analog electrical signals at a time, and converting them into digital signals, wherein the light inputted to said photoelectric conversion device is transmitted light from an original film to which light has been applied, said photoelectric conversion device includes four single-color photoelectric conversion devices corresponding to said four basic colors, respectively, and said four single-color photoelectric conversion device accumulate therein charges corresponding to the inputted light for predetermined accumulation times differing from one another, wherein said selection circuit selects the analog electrical signals outputted from three devices of said four single-color photoelectric conversion devices which are longest, second longest and third longest in said predetermined accumulation time, at the image reading of a first main scanning line, and selects the analog electrical signals outputted from the three devices of said four single-color photoelectric conversion devices which are longest, second longest and fourth longest in said predetermined accumulation time, at the image reading of a second main scanning line adjacent to said first main scanning line, and wherein said image reading apparatus further has an adding circuit, said adding circuit adds together the digital signals corresponding to the outputs of the single-color conversion devices which are longest and second longest in said predetermined accumulation time, obtained by the image reading of said first and second main scanning lines, for each pixel.